Photon momentum is p=E/c = hf/c depends of the frequency of light.

Temperature concept is mostly unrelated to photons, except in Black body radiation you can relate the two. This is a long subject, read about it. Thus you can tell the temperature of the sun, from the position of maximum intensity of its radiation.

Generally, temperature is the result of the speed of molecules in the corresponding medium.

The equipartition theorem assigns kT/2 per degree of freedom, so with simple molecules you get 3/2 kT for average kinetic energy of one molecule in classical statistics. k is Boltzman constant and T is temperature.

This is the result for Maxwell-Boltzmann statistics for clasical gases.

For quantum gases things are different, you have to read books on statistical mechanics.

A bose Einstein condensate is the result of Bose Statistics, one of the two quantum statistics. The other is Fermi Dirac.

You can talk about temperature in solids through phonons, something like the analogue of photons in space.

I know all that you are saying. My question is on physical processes. Maxwell E predict E and M chasing each other in an oscillatory way. What imparts them the momentum?

In Amperes Law we assume motion of electrons. In Faradays Law we assume there is an implied mechanical motion through a change of magnetic field, or ir is derived by change of current, which is again the change of motion of electrons.

So we have not said who is the source of momentum to the photon?

I think the Maxwell theory on EM phenomena is a macroscopic classical theory which says nothing about

photons, which only arise when the radiation is interacting with matter. So one cannot answer based only on Classical EM.

You have to go to a more quantum perspective, maybe the

QM book by Schiff will help you with some answers, in the last chapters, which has Maxwell tied to QED.

Then there are many results in Physics that are purely empirical, you do not know the why.

I do not like regurgitated answers. I am looking at answers which are not answered till now. There are many holes in Physics and most of the people accept them without questioning further.

The question is simple: what process gives the photon its momentum? Think the works of De Broglie along these lines.

Well consider the emission of radiation from transitions

between electronic levels

Then delta(E)=hf

I previously said that frequency f and photon momentum

are related.

So the energy difference between the levels then determines

the photon momentum. Is that concrete enough for you?

You are regurgitating without deep insights. We all know frequency and momentum are connected through Wave Equation.

You asked

what process gives the photon its momentum?

I answered. What more is pretended?

delta(E)=hf is a QM result.

E=pc comes from the Einstein energy formula without rest mass.

The de Broglie result

p=h/lambda

also applies to photons, as well as massive particles.

I think you are too deep into common mainstream of repeating facts without answering many questions unanswered.

What is the physical process that makes a photon get absorbed and then emitted? I want a white box and not a black box statement.

What is the physical process by which 2 Photons are emitted in collision of positron and electron. What is the physical process by which 2 Photons of great 1022 MeV energy give electron and positron.

So what is the source of "k" in Maxwell E, which is a macroscopic Plane Wave approximation, but points to "k" of a particle/wavelet photon?

p=h/lambda =h/2pi 2pi/lambda = hbar k

The wavevector k is proportional to the momentum, depends on wavelength. A way of joining wave and particle properties.

Many ways of saying the same thing.

I suppose this is the k you are talking about.

No. You do not get it.

Energy and Momentum are related. The rise in temperature makes many molecules and photons pick up Energy. The pure EM part never creates momentum.

Sunil k srivastava.

The physical process whic gives rise an electron-positron pair, when gama ray photon of enery equal to or greater than 1.022Mev passes near heavy nucleaus is due to the negative point energy.

As we considered the zero point energy, there also exist the negative point energy which is further below than zero point energy and to remove electron from these states 1.022Mev energy required for it and the energy greater than 1.022Mev is then used to give electron kinetic energy i.e 1.022 Mev is the lower bound. And the positron which also produces in the proces is due to law of conservation of charge.

I think its enough to understand...